import math as mt
x = list(map(float,input().split()))

a = ((x[0]-x[2])**2)+((x[1]-x[3])**2)


print(mt.sqrt(a)) import math as mt math x = list(map(float,input().split())) x list(map(float,input().split())) list map(float,input().split()) map float input().split() ().split () input split a = ((x[0]-x[2])**2)+((x[1]-x[3])**2) a ((x[0]-x[2])**2)+((x[1]-x[3])**2) (x[0]-x[2])**2 x[0]-x[2] x[0] x 0 x[2] x 2 2 (x[1]-x[3])**2 x[1]-x[3] x[1] x 1 x[3] x 3 2 print(mt.sqrt(a)) print mt.sqrt(a) mt.sqrt mt sqrt a x = list(map(float,input().split())) list(map(float,input().split())) x a = ((x[0]-x[2])**2)+((x[1]-x[3])**2) ((x[0]-x[2])**2)+((x[1]-x[3])**2) a
import math as mt
x = list(map(float,input().split()))

a = ((x[0]-x[2])**2)+((x[1]-x[3])**2)


print(mt.sqrt(a))
